It sounds like it wasn't.
It sounds like an assumption of liability was done, and you were only 5 months into your contract, so you had 19 months left. Well, when you do an AOL, if you have more than 12 months left on the contract it just defaults to a 12 month contract, but your upgrade dates stay the same. So, it's possible that your contract could be up in August, but your upgrade date is a little further out.
In your situation, it would sound like the last upgrade was done in June, 2010. Then you did an Assumption of Liability in August. So your contract is up in August, but your upgrade still isn't until February, 2012.
Check the exact date you actually did an upgrade. If it was actually 20 months ago, call customer service, they will be able to check that and get it corrected.